Reduction of barnacle recruitment on micro‐textured surfaces: Analysis of effective topographic characteristics and evaluation of skin friction

This study investigates five designed micro‐textured surfaces and their effects on barnacle fouling and hydrodynamic drag. Three of the micro‐textures were developed in the present study and evaluated together with two commercial riblet films. All micro‐structures were arranged as longitudinal grooves with different profile depths, widths and angles of inclination. In field tests the recruitment of the barnacle Balanus improvisus on micro‐textured surfaces and smooth controls was evaluated. All micro‐textured surfaces reduced recruitment, and the most efficient texture reduced recruitment by 98%. For some micro‐textures the reduction of recruitment declined as settlement intensity increased. In a correlative analysis, the trigonometric inclination of the micro‐structures explained most of the recruitment reduction. The steepest angle of inclination caused a massive reduction in barnacle settlement. Surface micro‐structures may affect the boundary‐layer flow and the hydrodynamic drag (skin friction) of the surface. The skin friction was empirically measured in a flow channel using a sub‐set of the tested micro‐textures. The measurements of skin friction showed that the orientation of the microstructures is important, with a minimum friction when the grooves are parallel to the flow. For one of the micro‐textures the skin friction was ca 10% lower compared to a hydraulically smooth surface. It is concluded that, depending on the flow speed, micro‐textures will not significantly increase skin friction when arranged parallel to the flow, even at moderate protrusion through the viscous sub‐layer.     

USE OF THE DISCRIMINANT FUNCTION TO PREDICT THE NUMBER OF CONSUMERS WHO DISCRIMINATE

Three brands of chocolate milk were evaluated for liking, sweetness, creaminess and natural flavor by 48 consumers, using 100mm line scale. The mean sweetness score for one brand was significantly different to the other two and all other attributes were similar. Discriminant analysis on scores from the line scales showed that 63.8% of the evaluations of the least sweet brand (Brand A) were classified by the discriminant function as belonging to the least sweet brand. 19.1% of the scores for Brand B and 17.0% for Brand C were classified as identifying Brand A. A simple count of the number of consumers ranking each brand as least sweet showed that 63.8% chose Brand A, 19.1% Brand B and 17.0% Brand C. This suggests that the discriminant function provides a measure of the proportion of assessors who can tell the difference or, a measure of the degree of confusion between samples.     

THE RELIABILITY OF MDPREF TO SHOW INDIVIDUAL PREFERENCE

Liking rating data of 8 pigmeat products from 99 Australian females aged 25-45 was analyzed using MDPREF. A line scale extended past the anchor points, 100 mm long and anchored by the words 'dislike extremely' and 'like extremely' was used. Liking was judged on the product name alone, no products were actually tasted. MDPREF configures products and consumers so that individual preferences (or product order preference) can be obtained. The order of product preference from the rating scores and order of product preference from the MDPREF analysis for each consumer was matched. It was found that the preference order for each consumer from the MDPREF map matched the order shown by rating scores in about 25% of cases. MDPREF produced 17% of consumers who had no products in the correct position for the preference order. Only 1% of consumers had all eight product preferences in the correct order.     

COMPARISON OF ATTRIBUTE LIKING AND JAR SCALES TO EVALUATE THE ADEQUACY OF SENSORY ATTRIBUTES OF MILK DESSERTS

Just-about-right (JAR) scales and attribute liking questions are usually used to study consumer perception of the sensory characteristics of food products. The aim of the present work was to compare the performance of attribute liking and JAR scales to evaluate consumers' perceived adequacy of flavor and texture of milk puddings. Two groups of consumers were asked to evaluate eight milk desserts using (1) overall liking followed by attribute liking for texture and flavor and (2) overall liking followed by JAR scales for thickness, creaminess, sweetness and vanilla flavor. Overall liking scores were significantly different when JAR scales or attribute liking questions were considered. Texture, flavor and overall liking scores were highly correlated to each other, providing the same information. JAR scales correlated better with the intensity of sensory attributes evaluated by a trained sensory panel, being JAR percentages a reliable tool to study the adequacy of sensory attributes.

PRACTICAL APPLICATIONS

Results from the present work showed that consumers might not be able to independently evaluate their liking of different sensory attributes of a product. For this reason, the use of attribute liking questions for studying the adequacy of sensory attributes in complex products would not be recommended. JAR scales were better indicators of the adequacy of sensory attributes. Consumers were able to independently evaluate texture and flavor attributes using JAR scales. However, the influence of JAR scales on overall liking scores should be taken into account when including these scales on consumer studies.     

不同质地背景对自由飞行蜜蜂跟踪运动目标的影响

本文研究了不同质地背景对自由飞行蜜蜂跟踪运动目标的影响.质地背景采用了灰度调制度和空间频率均可调整的双正弦波图形构成,其灰度对比幅度为64级,平均灰度为32,运动目标是一个直径3.4厘米,灰度值为32的均匀灰色圆盘.当幅度调制度从小(31%)到大(93%)变化时,蜜蜂目标跟踪系统的水平增益S1也随之增大.这是由于较大的调制度可以给予蜜峰以较大的背景与目标之间的灰度对比.从短(7.6毫米)到长(38毫米)改变质地背景的空间波长,结果显示,在空间波长为30.4毫米处有一个明显的锐起峰值.计算结果表明,质地背景与目标之间在目标边缘的灰度反差,其最大值恰好发生在空间波长等于30.4毫米的情况下.这充分说明,S1的锐起峰值完全是由于形成于此的强烈灰度反差造成的.这一结果表明:无论目标运动与否,无论背景是均匀的还是质地的,背景与目标在目标边缘形成的灰度反差对蜜蜂发现并且跟踪目标起着重要乃至决定性的作用.     

THE ROLE OF THE KNOWLEDGE OF COLOR AND BRAND NAME ON THE CONSUMER'S HEDONIC RATINGS OF TOMATO PUREES

The objective of study was to assess the influence of the knowledge of color and brand name on consumer response to tomato purees. From focus group interviews it was found that taste and odor of fresh tomato were the most important drivers of consumer choice. To quantify that information a questionnaire was developed and it was submitted to fifty consumers of tomato puree. The questionnaires answers confirmed those coming from the focus group, although same discrepancies were found with those derived from the consumer test. Results showed that color and brand name seemed to be more important than taste and odor of fresh tomato, in fact those attributes, when consumers were tasting samples, affected not only hedonic judgments but sensory perception as well. Finally physico-chemical parameters derived from instrumental measurements have been compared to sensory data by means of PCA in order to validate the consumers'assessment of sensory attributes of tomato puree.     

A THURSTONE-COOMBS MODEL OF CONCURRENT RATINGS WITH SENSORY AND LIKING DIMENSIONS

A popular product testing procedure is to obtain sensory intensity and liking ratings from the same consumers. Consumers are instructed to attend to the sensory attribute, such as sweetness, when generating their liking response. We propose a new model of this concurrent ratings task that conjoins a unidimensional Thurstonian model of the ratings on the sensory dimension with a probabilistic version of Coombs' (1964) unfolding model for the liking dimension. The model assumes that the sensory characteristic of the product has a normal distribution over consumers. An individual consumer selects a sensory rating by comparing the perceived value on the sensory dimension to a set of criteria that partitions the axis into intervals. Each value on the rating scale is associated with a unique interval. To rate liking, the consumer imagines an ideal product, then computes the discrepancy or distance between the product as perceived by the consumer and this imagined ideal. A set of criteria are constructed on this discrepancy dimension that partition the axis into intervals. Each interval is associated with a unique liking rating. The ideal product is assumed to have a univariate normal distribution over consumers on the sensory attribute evaluated. The model is shown to account for 94.2% of the variance in a set of sample data and to fit this data significantly better than a bivariate normal model of the data (concurrent ratings, Thurstonian scaling, Coombs' unfolding model, sensory and liking ratings).     

DESIGNS TO BALANCE THE EFFECT OF ORDER OF PRESENTATION AND FIRST-ORDER CARRY-OVER EFFECTS IN HALL TESTS

The problem of balancing out the effect of order of presentation and the carryover effect of a preceding sample over a series of presentations of the same set of samples is addressed. A series of designs developed by Williams (1949) are used. The method of calculation is given. Tables containing about 50 consumers of each design for presenting from 4 through to 16 samples are given.     

SENSORY PROFILE DESCRIPTION OF MOZZARELLA CHEESE AND ITS RELATIONSHIP WITH CONSUMER PREFERENCE

The aim of this work was to set up the sensory profile and consumer preference test of three different Mozzarella cheeses (from full-fat cow milk, from low-fat cow milk and from full-fat water buffalo milk). The most remarkable difference in composition was the fat content. Nine commercial Mozzarella cheeses (three for each type) were evaluated in triplicate by a trained panel consisting of 10 assessors. Six Mozzarella cheeses (two for each type) out of the nine samples were selected and used for the preference test by 105 consumers. The three different Mozzarella cheeses were sensorially well differentiated. A good discrimination between the Mozzarella cheeses was obtained using the internal preference map method. The combination of cluster analysis and internal preference mapping has lead to a deeper understanding of consumer liking for Mozzarella cheeses.     

EFFECT OF QUESTIONNAIRE DESIGN AND THE NUMBER OF SAMPLES TASTED ON HEDONIC RATINGS1

A total of 450 consumers participated in a test to determine whether questionnaire length, presence of key diagnostic questions or serving position affected their hedonic discrimination among yellow cakes. Consumers evaluated four yellow cakes representing a 2 × 2 factorial design of texture and flavor flaws. They used one of the following six questionnaires: only a 9-point hedonic scale, a 9-point hedonic scale with open end questions, and four others comprising a 2 × 2 factorial design with two levels of questionnaire length and two levels of questionnaire completeness. Neither the presence of key attribute questions nor the length of the questionnaire affected the value or the sensitivity of the judges’ overall liking scores. Samples tasted first received higher hedonic scores than those same samples tasted second throughfifth. Judges could discriminate among the samples on the basis of overall liking best when samples were tasted fourth or fifth.     

CONSUMER INVOLVEMENT AND EVALUATION OF GREEN PEAS1

This paper reports the effect of consumer involvement on overall acceptance of frozen peas used in green salad and the effect of consumer involvement on the consumer's ability to perceive variations in a set of physical/chemical characteristics such as AIS (Alcohol Insoluble Solids) and color. The results reveal that consumers with high involvement evaluate 16 experimentally varied pea samples more in accordance with quality indicators used in the industry than consumers with low involvement. In our study 61% of the consumers were highly involved. For low involved consumers there was no relation between average acceptance and the quality indicators used by producer/retailer and retailer/consumer. High involved consumers could identify more of the physical/chemical variation in the pea samples than the low involved consumers. The results stress the importance of a preliminary segmentation of consumers. The low involved consumers do not seem to have any specific preferences for any of the samples included in the study although samples are varied considerably with respect to size, color and amount of sucrose. It may be considered as indifference. An obvious conclusion to draw from the results of this study is to concentrate on the highly involved consumers in further product development.     

THE EFFECTS OF COLORED TEXTURED SOYBEAN PROTEIN (TSP) ON SENSORY AND PHYSICAL ATTRIBUTES OF GROUND BEEF PATTIES

Defatted soybean flour mixed with a combination of 0.03% Red No. 40 and 0.01% annatto ( Bixa orellana ) colorants was extruded into textured soy protein (TSP) in a counter-rotating twin extruder to produce a red-meat like product suitable for hamburger patties. Ground beef patties were processed replacing the meat (15 and 30%) with resulting hydrated textured soybean protein (TSP) prepared with and without the colorants. The resulting cooked patties were evaluated by eight trained judges for tenderness, juiciness, number of chews, beef flavor and overall flavor quality using a nine point nonstructured horizontal scale. Other patty characteristics examined included cooking losses (weight loss and diameter reduction) and color, by tristimulus colorimetric measurement. The results from sensory analysis revealed that ground beef patties with high TSP level were more tender than control, and they had less beef flavor and overall flavor quality. Weight loss was not significantly (P > 0.05) affected by TSP level but the patties with 30% TSP showed less shrinkage than the others. Results of the study suggested that while patties with 15% TSP had sensory attributes similar to the control, adding 30% TSP with coloring significantly (P < 0.05) increased the redness of the patties.     

USAGE BEHAVIOR OF MEAT PRODUCTS BY AUSTRALIANS AND HONG KONG CHINESE: A COMPARISON OF FREE CHOICE AND CONSENSUS PROFILING

Australian and Hong Kong Chinese male and female consumers, aged 20 to 30 years, evaluated a range of 16 meat products using two questionnaires. One questionnaire comprised the 12 most frequently used terms by consumers to describe how, when and where they would most often consume each product. The alternate questionnaire for each individual comprised free choice vocabulary. Half of each consumer sample used the consensus questionnaire and the other half, the free choice questionnaire first, and indicated how often they would consume each meat product in the various contexts listed using graphic line scales of 100 mm anchored at either end by the words ‘never’ and ‘always’. After an interval of time, the alternate questionnaire was completed. It was found that similar conclusions can be drawn about major contextual dimensions either by principal component analysis of data from a consensus questionnaire or by generalized Procrustes analysis of data from free choice profiling.     

THE LIFE CYCLE OF PEDIASTRUM SIMPLEX1

A sexual cycle and a newly discovered mode of asexual reproduction by azygotes arc described for Pediastrum simplex. In the sexual cycle isogametes from colony cells fuse in pairs, develop into zygotes, which grow and divide, producing motile cells which become angular polyeders. Polyeders may divide internally to form 4-celled colonies, or they enlarge, cleave, and produce zoospores or nonmotile cells. Zoospores are released in vesicles, swarm, adhere to each other, and form, flat colonies I cell thick. The nonmotile cells adhere to each other, enlarge, break out of the polyeder, and become spheroidal colonies. In the asexual cycle, nonfusing gametes, and motile cells derived from colony cells, become 4-spined azygotes which enlarge, divide internally, and release motile cells developing into polyeders. These polyeders develop further like those from zygotes.     

ELECTRON MICROSCOPIC RADIOAUTOGRAPHIC STUDIES OF THE CAROTID BODY FOLLOWING INJECTIONS OF LABELED BIOGENIC AMINE PRECURSORS

Adult Syrian hamsters were given a subcutaneous injection of reserpine 3 days before an intraperitoneal injection of ³H-3,4 dihydroxyphenylalanine or ³H-5, hydroxytryptophan and the carotid bodies were subsequently prepared for electron microscopic radioautography. Other Syrian hamsters were given a subcutaneous injection of reserpine and the carotid bodies were subjected to a sensitive cytochemical test for the detection of unsubstituted amines. These studies were made to determine whether the labeled amine precursors were incorporated into the cells and to see whether the parenchymal cells were affected by reserpine treatment. Material from hamsters treated first with reserpine and subsequently injected with ³H-3,4 dihydroxyphenylalanine or ³H-5, hydroxytryptophan exhibited reduced grains of silver over the cells which were associated mainly with the dense cores of the cytoplasmic granules. These studies offer evidence that the granules of the carotid body incorporate catecholamine and indolamine precursors. Material from hamsters incubated for the presence of unsubstituted amines gave a positive reaction (opaque cytoplasmic granules) for catecholamines but not for indolamines. The latter substances may not be present in quantities sufficient to register a positive reaction in the cytochemical test. The opaque granules, indicative of the presence of catecholamines, decreased in density after reserpine treatment. 5 days after one reserpine injection the granules had regained opacity and were comparable to those seen in the control cells.     

OBSERVATIONS ON THE FINE STRUCTURE OF OEDOGONIUM. III. MICROTUBULAR ELEMENTS IN THE CHLOROPLASTS OF OE. CARDIACUM12

The expansive, reticulate cliloroplasts of the filamentous green alga Oedogonium tardiacum were found to contain microtubular elements with an outside diameter of about 270 A. These microtubules have been examined in the chloroplast stroma of vegetative cells, zoospores, zoospore germlings, and eggs. They may occur singly or, more commonly, in groups or bundles of 2 to as many as 30. In longitudinal section these microtubules show a regular pattern of slightly oblique cross striations and the margins appear rough. They bear little structural resemblance to the more familiar and slightly smaller microtubules found in the cytoplasm external to the cliloroplasts. Their overall appearance suggests that each is constructed of 2 helically wound, ribbon-like units that are approximately 155-175 A broad and 45-55 A thick. The 2 units of this proposed double helix appear to lie in juxtaposition at a pitch of 17-27 deg. The dimensions of each unit, or helix, are such that it could conceivably be constructed of 3 filamentous subunits similar to those already described in the literature for other microtubular elements.